Heya dont know if your using PCIX card but with a 5 drive RAID 5 (Maxline 16MBCache) setup on a 1820A from Highpoint i get 240MB empty 180-170 when 3/4 full
to me SATA II for now is useless since drive are not yet using the full band of SATA 1
hope it helps
“Dont Fear Evolution….BE IT”